Red growths on maple leaves won’t harm tree
Q: There are shiny red growths on many leaves on my silver maple this year. The growths look similar to a lady bug without the spots. They are firmly attached to the leaf and cannot be scraped off or removed by spraying water on the leaves. Some of the affected leaves have already begun to fall. What are these growths and will they harm the tree?
A: What you’re seeing are maple bladder galls. Galls are plant structures made by insects, in this case eriophyid mites. The galls typically evolve from developing plant tissue, so they were formed during the leafing-out process this spring. At that time, the galls were not nearly as noticeable because they were light green in color.
There are scores of different galls that form on different species of plants and different plant parts. Galls that form on leaves, such as maple galls, are more of a curiosity than a concern. They will not hurt the health of the tree.
Q: Some of the leaves of my buckeye tree are turning black and falling to the ground. I’ve also noticed a buckeye tree in a local park with this condition. Is there a disease affecting buckeyes?
A: The damage you’re seeing on the buckeye trees is likely from a petiole borer. The petiole is the small stalk that attaches the leaf to the stem, and there are several insects that bore into it. That causes the leaf to turn black, droop and fall from the tree.
These insects rarely cause significant leaf loss, so no controls are necessary. The overall health of the tree should not be affected.
Q: The very top branch of a beautiful, 8-foot-tall blue spruce in our front yard recently started to droop. This branch seems to be drying out and dying. What could be causing this, and should we prune the top branch?
A: The damage you describe is the telltale sign of the white pine weevil ( for Latin geeks). The insect now seems more interested in attacking blue spruces than its namesake white pines.
Adults spend the winter in the litter under the trees and in early spring move to the tip stem (or leader) of the tree to burrow in and lay eggs. The larvae then feed on the inside of the stem, causing it to droop and eventually die.
The best approach is to prune off the affected tip stem now, before the larvae become adults. Then burn or otherwise destroy it.